1. Field of the Invention
The invention relates to an articulating device and method of using. In addition, the invention relates to the use of the articulating device for steering medical devices such as the distal portion of medical devices typically used in minimally invasive surgery.
2. Description of Related Art
Rigid instruments, which may, for example, be catheters, graspers, or other tools, limit the ability of the surgeon to access the interior portions of the body. By having articulateable distal portions this adds an extra degree of freedom, thus reducing the need for changing tools during a procedure, and as a result reducing the time needed for the procedure to the mutual benefit of surgeon and patient alike.
As already stated the majority of tools used in these procedures are rigid. There are a variety of devices which have a degree of steerability added via a fixed curve being introduced in the distal end, and some devices which have steerable tips. Examples of steerable tips can be found in commonly owned and copending application Ser. No. 07/903,587 and U.S. Pat. No. 4,934,340 ("Wendel"), and U.S. Pat. No. 5,114,403 ("Clarke"). In many of these devices the distal tip, on being articulated, suffers from the problem of not being able to sustain any appreciable end loading, and hence buckles easily. It is also extremely desirable for the devices to be hollow, or in the form of a cannula, such that any debris generated during a procedure may be aspirated from the operation site without the need for extra equipment. Thus, there is a need in the art for small diameter devices which freely articulate, are capable of resisting substantial end-loading, and due to their tubular nature enable simultaneous removal of debris via fluid flow.
Various devices are known for steering medical devices such as catheters. For instance, steering mechanisms are discussed in WO92/14506 ("Middleman") and U.S. Pat. Nos. 4,353,358 ("Emerson"); 3,470,876 ("Barchilon") and 4,245,624 ("Komiya").
Middleman discloses a device for insertion into a body, the device including an elongated tube or cannula, an elastic member for bending the cannula and a straightener preventing the elastic member from bending the cannula. The straightener and elastic member are capable of relative axial movement so that the straightener can be positioned to prevent or allow the elastic member to bend the cannula. The elastic member can be formed from a superelastic shape memory alloy. In another embodiment of the device, two elastic members are housed in parallel lumens of a cannula. The portions of the elastic members which are housed within the distal segment of the cannula are curved and can be positioned within the lumens such that they tend to curve in opposite directions. The elastic members can be identically curved and of the same elastic material such as a superelastic shape-memory alloy whereby each applies a force opposite to the other so that the net effect is that the distal segment is straight. The lumens permit rotation of the elastic members therein and the elastic members can be rotated together, or in unison, to bend the distal segment. In this case, a stiffener is not needed so that the cannula can remain flexible.
Emerson discloses a disposable sigmoidoscope having a tubular portion of plastic material wherein a free end is weakened by providing one or more cut-outs or notches or by making the side of the tubular portion thinner. An operator cord member of wire, plastic or string member is attached to the free end and extends along the outer surface of the segments between the cut-outs, on the inside of the segments or through the weakened side of the device. Pulling on the member allows the tubular member to be bent somewhat but not so much that the operator can no longer see through the passage through the tubular member. A protective outer layer or sheath covers the cut-outs in order to prevent discomfort to the patient during insertion and withdrawal of the device and prevent material from entering the device through the cut-outs.
Barchilon discloses a 1/8 to 2 inch diameter catheter including an outer tube, an inner tube and a rigid end piece connecting the distal ends of the inner and outer tubes. The end piece has a flange and four tensioning cords are attached thereto such that each cord is offset 90.degree. with respect to each other. The inner and outer tubes are of flexible material such as a silicone compound having a durometer of 48. The cords are of material such as wire or nylon and the catheter can be bent in any desired direction by pulling on one or more of the cords.
Komiya discloses an endoscope having an observation optical system, a flexible plastic guide tube and a wire, each of which is located in a respective one of three channels extending longitudinally through a distal end of the endoscope. The guide tube is movable longitudinally beyond the distal end of the endoscope and the wire is attached to a distal end of the guide tube for bending the guide tube. When the guide tube is empty, liquid can be sprayed from or sucked into the distal end thereof. On the other hand, a medical implement such as forceps can be inserted into the guide tube and the wire can be used to bend the guide tube and medical implement toward a prescribed location in a body cavity. The guide tube can be made more flexible by using a plastic material foamed at a progressively higher rate at the distal end thereof. Alternatively, the guide tube can be made thinner at the distal end thereof or the guide tube can be surrounded by a coil of plastic or metal which has a progressively larger pitch toward the distal end of the guide tube.
It would be desirable in the medical field to have a steering device which provides resistance to end-loading while permitting a wide range of movement of a distal end of a medical device.